sui juris

from Bouvier's Law Dictionary, Revised 6th Ed (1856)
SUI JURIS. One who has all the rights to which a freemen is entitled; one 
who is not under the power of another, as a slave, a minor, and the like. 
     2. To make a valid contract, a person must, in general, be sui juris. 
Every one of full age is presumed to be sui juris. Story on Ag. p. 10. 
    

[email protected]